Ok, first off...I think that whatever Raptor you buy, whether Gen 1 or Gen 2, you will enjoy the truck...Cause the truck IS awesome!
But here is my opinion (FWIW) to your question from a former all Chevy guy and one who has had 6 Vettes (4 Z06s):
EVERY single time I have bought a "lower optioned" vehicle, even a nice one, I always wished I had loaded it up with all the "unneeded stuff" that once you have, you don't ever want to be without! (higher resale too)
So for me, and again IMHO, I would save up until you can get the "full-meal-deal"...You will love the tech package, adaptive cruise...and leather.
Regarding future model improvements...probably gonna happen, always does, and you can bet that Ford, like all other car makers, have a strategic plan that INCLUDES minor to major model-year improvements to spike and encourage sales...So yes, changes are coming (at least minor ones in the next couple years for the Raptor...I'm also betting against a V8 until at least Gen 3)
BUT, if you spend life waiting for the next better "thing" you will never get anything...Something better will always happen... So buy what you like now, MOD IT, and "enjoy the ride"
Lastly, I DD my Raptor, and after a couple week adjustment from "driving on the ground" with the Vette, the Raptor will feel right at home; with a more challenging parking issue for sure... but no worse than any other truck. Besides, if you are the "typical" Vette owner... you always park away from everyone else anyway... so, with the Raptor, you all set!
Good Luck with the decision...